Currently, oil refinery companies have operated processes of converting heavy crude oil into light crude oil having higher economic value. To smoothly operate the processes, hydrodesulfurization (HOU HDS) and hydrodemetallization (HDM) catalysts for removing much sulfur and/or many heavy metal components contained in the heavy crude oil have been used and exchanged into new catalysts three or four times a year due to the durability of the catalyst itself.
Although various kinds of desulfurization catalysts are used for various processes, the desulfurization catalysts are typically used in oil refinery factories. An Ni—Mo/Al2O3 or Co—Mo/Al2O3 catalyst is commercially used as the hydrodesulfurization catalyst. Mo, Co and Ni components remain on the spent hydrodesulfurization catalyst intact without any loss, but a large amount of vanadium, contained in heavy crude oil is deposited on the spent hydrodesulfurization catalyst instead.
Although there is required to economically recover variable metals such as V, No, Co and Ni existing in a spent catalyst, the spent catalyst is coated with waste oil of 20% or more including a sulfur component and is classified as a specified waste among environmental wastes, so that it is not easy to treat the spend catalyst.
Therefore, since the valuable metals contained in the spent catalyst, of which the mineral resources are rare and the bearing areas are regionally distributed, are very expensive and entirely dependent on import, there is a need to provide a method of effectively recovering the valuable metals from the spent catalyst containing the valuable metals.
As a related art, there has been disclosed a method of separating and recovering V2O5, MoO3 and NiO from a spent catalyst containing vanadium, molybdenum and nickel in Korean Unexamined Patent Publication No. 10-2009-0132462 (published on Dec. 30, 2009).